It is well known in the art that many types of signals that are used to convey information carry superfluous or redundant information, and that the signals or portions of signals that convey the superfluous or redundant information may be discarded to increase the density or reduce the number of information-carrying signals without loss of desirable information. It is also known that the density or number of signals may often be respectively increased or reduced further, thereby sacrificing only some quality of the desirable information without loss of the basic desired information content. Techniques for achieving these increases in the density or reductions in the number of signals are commonly called compression techniques, and many are known in the art.
It is also known in the art to equip a signal-processing system with the ability to perform a plurality of compression techniques and leave it up to a user of the system, or to the system itself, to select which one of these techniques is actually used, as disclosed, for example, in U.S. Pat. No. 4,791,660.The selection may be done statically, such as by administratively specifying which compression technique will be used for all signal processing, prior to activation of the processing system. Or, the selection may be done dynamically, such as by every application program specifying to the system the compression technique that it desires to use for processing relating to that application program, as taught by U.S. Pat. No. 5,133,004, or by constantly monitoring the efficiency of compression being performed and automatically changing the compression technique being used in order to constantly adapt the system to changing characteristics of the signals being processed, as taught by U.S. Pat. No. 4,730,348.
All known signal-processing systems have finite signal transmission throughput and/or signal storage capacity. Since the selection of the compression technique affects the density or the number of signals that must be stored or transmitted to represent a given amount of information, the selection of the compression technique directly affects the information throughput or information storage capacity of a processing system. However, as was also alluded to previously, the selection of the compression technique also affects the quality of the conveyed or stored information. Hence, the selection of the compression technique normally involves a tradeoff between throughput and/or storage capacity on the one hand, and signal quality on the other hand.